Tuesday, April 30, 2013

An Egg Timer

I just had a perfectly cooked boiled egg. That's not terribly unusual. The unusual part is that for once I have confidence that I can do it again whenever I want. All thanks to a brilliantly designed egg timer.

Sabrina found this when we were wandering through Crate and Barrel. I'm going to provide some info on exactly how it works, since the packaging leaves a little to be desired.

The timer is simply a clear plastic egg with a layer of temperature sensitive material in the middle. It is placed in the boiling water with the eggs, and the red portion slowly changes to black as the eggs cook.

This is what it looks like as time progresses:

Note the difference in how the scale looks between the first picture and these two. When the egg is under water, the scale is easier to read, partially due to the curvature of the top surface.

I store it in the fridge with my eggs. I figure it is important that they start off at the same temperature. Then I drop it into the boiling water at the same time as the eggs.

The brilliance of this design is that it doesn't matter what temperature the water is. (Like if you add a bunch of eggs to a small amount of water, if you cook at a different altitude, if you sometimes salt the water, or even if you turn off the heat at some point.) The time fluctuates, but the timer compensates and reads correctly based on heat transfer. Not bad for $5.

The one downside is that there is no audible alert that your eggs have reached the desired level of hardness. You have to check on it periodically. For me, this is not a big deal. I have started cooking eggs while doing other things in the kitchen. (Like washing dishes, cleaning, cooking, etc.) This keeps me in the same room, so it is easy to glance into the pot every few minutes  (Or to fish out the timer with a spoon if it is too difficult to see through the bubbling water and steam.)

Tuesday, April 16, 2013

Mash Starch Test

I homebrew beer. I haven't talked about it much since February 2012 where I described the chest freezer I use to control fermentation and lagering temperatures.

Today I'm going to describe an experiment Sabrina and I did testing the effectiveness of my mashing procedure.

Mashing is the first step in making beer from malted barley and other grains. During the mash, you heat a mixture of crushed grain and water up to certain temperatures. You hold the temperature constant at one or many different points to allow the naturally occurring enzymes in the malt to convert starches into simpler sugars. Mashing usually involves holding temperatures for up to 90 minutes.

One method of testing the progress of this conversion is to perform an iodine starch test. A good description of what is going on can be found here. In brief, when an iodine solution is exposed to starch, the iodine changes color from dark brown to intense purple/black. Once all the long-chain starches are broken down, the iodine test will be negative. There will be no color change when the iodine solution is mixed with the wort. (Wort is the liquid sugar solution produced in the mash, or unfermented beer.)

The first experiment we did was to perform the iodine test every 10 to 15 minutes during a 90 minute mash rest. We also measured pH using test strips. We recorded time and temperature on the end of each test strip.  Here you can see the results:

The test was done by placing several drops of wort on a piece of chalk. A medicine dropper makes this much easier, just be sure to rinse it well between samples. Next, a couple drops of iodine solution were placed on the same piece of chalk. If you are careful to ensure that the iodine drops cover both part of the chalk soaked in wort and part of the dry chalk, it is very easy to detect if a subtle color change occurs.  You can see this effect rather clearly in the 80 minute and 90 minute samples above.

One thing I was not expecting was that once the iodine and wort evaporated from the chalk, the color disappeared. You can see how the color from the earlier samples is fading away. The color of the pH test strips also faded away as they dried.

I still had questions after this first experiment. All samples had been taken from the drain at the bottom of the mash container immediately after the mash had been stirred up.

The next time I made beer, we continued the experiment and collected more detailed data. This time we took samples from various locations in the mash, both with and without stirring. The pH was written down at each step so this time I have an accurate record of pH changes. Samples were taken every 15 minutes during a 60 minute mash.

The sample at the start of the mash was taken immediately after stirring together the water and grain. There was a clear purple color. 15 minutes later, three samples were tested. One from the drain without mixing or stirring (N), one at the top of the mash where the grain and water are mixed together (T), and one from the drain after mixing (M).

Without mixing, there was no reaction. This leads me to believe that the enzymes rather quickly convert the starches that are dissolved in solution. The top and mixed samples showed varying degrees of reaction. My conclusion is that at the top, starches continue to dissolve into the wort from the grain, and after stirring, these starches are distributed throughout the mixture.

The results from the rest of the mash were relatively unexciting. The reaction showed negative at 30, 45, and 60 minutes. This indicates that starch conversion finished rather early. A negative starch test doesn't necessarily mean that the mash was finished this early since the enzymes will continue to break down sugars. However, it is a good indication that the mash is progressing well.

A quick word on the iodine solution used for this. I bought 10% providone-iodine solution from the first aid section of my local pharmacy. I then diluted it 10 to 1 with rubbing alcohol. This lightens the color of the iodine so that the more subtle purple reaction can be seen. Otherwise the iodine is very dark and can mask a partially positive reaction.

I have heard that this test also works well using iodophor, a no-rinse sanitizer that is often used in homebrewing. Simply dilute the iodophor 10 to 1 with rubbing alcohol and it should work the same.

The Container Store sells some amber glass bottles with built-in medicine droppers that worked very well for storing and dispensing the iodine solution. It made it easier to avoid spills, which is important since iodine stains.

A couple months after I did my experiments, I ran across an episode of the Basic Brewing Radio podcast that goes into great detail on the subject. If you are interested, look for the March 3, 2011 episode.

Tuesday, April 2, 2013

Adventures in Plumbing

My parents' house has a well that supplies their water. About a year ago, they had a less-than-competent contractor install a storage cistern and a booster pump. 

The contractor didn't anchor down the pump base, depending entirely on the weak PVC pipe and gravity to hold it in place against constant vibration. The electrical work he did had to be completely redone by someone else. The concrete cistern has leaked since day one, even after several repair attempts by the original contractor 

The pump started leaking much more recently, and much worse. What looks like a blurry water drop at the rightmost corner is a constant stream. This is what the leak looked like with the booster pump turned off and the piping downstream depressured. 

The first step I took was to disconnect the piping from the downstream union and I began to unscrew it from the pump. The pipe was loose! It wasn't even screwed in tightly. The piping configuration makes it impossible for the pipe to unscrew itself from the pump without disconnecting it downstream. Here is an overview of the pump and piping configuration. The piece that I removed comes out of the top of the pump and connects to the half of the union seen above and to the right of the opening.
Once I had the piping removed, I took a closer look at the opening on the pump. This is what I saw. 

There was metal sticking out into the bottom portion of the threaded opening. It looked like it might be flash left over from when the pump housing was cast. It deserved a closer look. 

That's strange... It looks like the threads abruptly stop.

Yup. The threads definitely stop. My only thought is that this might have been done to prevent threading the pipe in too far. If the pipe went past the inside surface of the pump case, it could hit the impeller (the part that spins.) 

Let's take a close look at the pipe I removed. 

The first thread at the end of the pipe is rather screwed up. It's as if it were tightened past that point where the threads in the pump stopped. It's almost exactly like that. 

At this point it is important to understand how tapered pipe threads are supposed to seal. The seal occurs at the threads as they fit tightly together. This site provides excellent diagrams of what should be happening. I have modified them below to illustrate what was happening in this specific case. When the pipe bottomed out, the threads were still loosely engaged. This allowed the water to leak out past the threads. I used a saw to shorten the pipe, removing the two smallest threads at the end. It was then able to seal tightly. A small amount of Teflon tape or joint compound seals any small gaps left in the imperfect threads. 

Below you can see the before and after pictures of the pipe. 

Based on what I showed above, this is what I think happened. The contractor screwed the pipe in place, tightened it to the point it became difficult, and then discovered that it leaked. When it leaked, he tightened the crap out of it until it stopped leaking, damaging the plastic pipe thread as it bottomed out in the hole. However, the threads were still not properly tight. The only reason it stopped leaking was due to the rather excessive amount of joint compound that was used. 

This is pipe joint compound. More is not better... 

The contractor saw the opening of the pump when he assembled the system. He failed to notice the rather obvious metal bits extending into where the pipe should be threaded. This is one more example of the shoddy job that was done all-around. 

Here is the final result after my repairs. If you compare this to the original picture of the leak, you can see that the pipe threaded in further. This created a good tight seal that should last. 

The leak started shortly after we had replaced the filter downstream of the pump. What we did must have been just enough to disturb the loose joint and start the leak. Both the inlet and outlet connections on the pump had the same problem, and were fixed the same way.